Nelson Paschoal
Active member
Hello friends, I´ve recently build this preamplifier from the schematic attached, but I did some mods, I would like to know from the experienced people if my mods were for good, they are:
- A 1uF cap in the input, followed by 1k res grid stopper
- changed 2M2 to 1M grid leak res
- eliminated the 10pF cap
- changed 12ay7 hard to find to 12AT7, and used 2K2/47uF in cathode first stage and 680R/47uF in cathode second stage
- 22k plate load in first stage and 100k plate load in second stage
Everything else was stock, except for the heater elevation, to minimize hum, I´ve noticed that this preamp doesn´t have much headroom, if someone want some readings I have signal generator and a scope.
Thanks for all!!!
- A 1uF cap in the input, followed by 1k res grid stopper
- changed 2M2 to 1M grid leak res
- eliminated the 10pF cap
- changed 12ay7 hard to find to 12AT7, and used 2K2/47uF in cathode first stage and 680R/47uF in cathode second stage
- 22k plate load in first stage and 100k plate load in second stage
Everything else was stock, except for the heater elevation, to minimize hum, I´ve noticed that this preamp doesn´t have much headroom, if someone want some readings I have signal generator and a scope.
Thanks for all!!!